Born in Newport, Watkins began his rugby career with Newbridge and Pontllanfraith before going professional with Newport in 1997. After scoring 35 tries (175 points) in 121 appearances over five seasons with the club, Watkins was signed by Llanelli. He was then part of the team at the dawn of regional rugby in Wales in 2003 and was part of the original Llanelli Scarlets regional side.
By 2007, he had become only the third player to reach 100 appearances for the region, following lock Adam Jones and prop John Davies. Watkins signed for Gloucester at the end of the 2007–08 season, midway through a three-year contract with the Scarlets.
On 3 August 2009, it was confirmed that Watkins would return to Wales and to the place where his professional rugby career began, signing for Newport Gwent Dragons on a two-year contract. He was released at the end of the 2010-11 season and retired soon after.
On 20 May 2013, it was announced that Watkins had developed a very rare pelvic cancer while studying for rugby coaching qualifications, but described himself as remaining "well and active."
